1. Field of the Invention
The present invention relates to shaped foamable structures that can be used, for example, to fill a cavity of a hollow structural member and to reinforce the hollow structural member. The present invention also relates to shaped foamable materials and attaching devices that can be used to support the shaped foamable materials in a closed box-like hollow structural member constructed from a plurality of plates, such as rocker panels, pillars and roof side panels of a vehicle body. After being expanded, the foam material increases the damping and sound insulating properties of the hollow structural member and increases the strength and rigidity of the hollow structural member.
2. Description of the Related Art
Japanese Patent Laid-Open Application Number 8-208871, and its corresponding U.S. Pat. No. 5,631,304, describe a foamable material for filling and reinforcing a hollow structure. In particular, a foamable material having block-like structure is taught and the block-like structure preferably has the same profile as the interior of the hollow structure. The block-like structure is placed against the interior of the hollow structure and heated in order to expand or foam the material, thereby filling and reinforcing the hollow structure.
It is an object of the present teachings to provide improved filling and reinforcing shaped foamable materials for hollow structures Preferably, by modifying the exterior shape of the shaped foamable material, the time required to completely foam the shaped foamable material can be significantly reduced. In addition, it may be possible to improve the expansion properties of the shaped foamable materials.
In one aspect of the present teachings, a shaped foamable material is formed from a plurality of foamable pieces. Preferably, the foamable pieces have clearances between each foamable piece, but are interconnected to each other for convenience of use. One or more support members or attaching means may be provided to position the interconnected foamable pieces within the cavity of the hollow structural member. Preferably, the interconnected foamable pieces do not contact the interior surface of the hollow structure. Instead, only the support members or attaching means contact the interior surface of the hollow structure. Therefore, the interior surface of the hollow structure can be painted after the foamable pieces are mounted inside the hollow structure, and before expanding the foamable pieces, because the foamable pieces do not block or cover the interior surface of the hollow structure.
With such interconnected foamable pieces, external heating for expanding the shaped foamable material can be effectively conducted throughout the entire shaped foamable material. That is, the clearances provided between the foamable pieces allow the entire shaped foamable material to be quickly and uniformly heated, thereby ensuring that the foam pieces expand at the desired ratio in a short amount of time.
Such a shaped foamable material is particularly advantageous for a hollow structure having a relatively large cross-sectional area, because the shaped foamable material should have a corresponding large cross-sectional area, so as to sufficiently fill the hollow structure cavity after expansion. The clearances provided within the present shaped foamable materials considerably reduce the time that it takes to completely foam or expand the shaped foamable material compared to foamable materials having a block shape. For example, if a block like foamable material is utilized for a hollow structure having a particularly large cross section, the center portion of the block like foamable material may not sufficiently foam or expand. Such problems can be overcome by the present shaped foamable materials.
In one aspect, the interconnected foamable pieces of the shaped foamable material can be integrally formed by injection molding. This alternative provides an easy to use shaped foamable material, if the cavities of the hollow structures have uniform lengths. In the alternative, the interconnected foamable pieces can be separately formed. After forming the individual pieces, the foamable pieces can be interconnected by a variety of means for connecting the foamable pieces. Therefore, the length of the shaped foamable material can be easily changed, if necessary.
The present teachings will become more fully apparent from the following description and claims as it proceeds in connection with the drawings.